I would recommend switching the leveling pet in and out before bringing in Draenei Micro Defender since Lil' often dies from that Batter, meaning Micro Defender resurrects as the end, meaning the carry pet gets no XP. Has happened this way for me every time I use this strategy, following it to the letter.

You might need a second Batter if the enemy has still too many HPs for Explode (560). But this comes with the risk that he will die from the Reflective Shield before the Explode (=> no XP for leveler).

Reworked my below strat. Tested over the last week or so. Notes and td script included (I think) Tolerances on this are pretty tight, fail conditions are a couple of crits by Oondasta or him getting off more than 2 of the attacks that I cant currently remember the name of but which damage the back row... looks kinda like a chain lightning effect.

Carry pet: Min health 900 - Max health 1399

Little Tommy Newcomer:27SQ:122CAJ:22181DA:ZL:P:900::6:1399:::N:Start with Darkmoon Zepplin. nnMissile - Oondasta forces swap to Dranei Micro DefendernIf Frill Blast is available use Shield BlastnElse use Batter until Dranei Micro Defender dies and resurrects...n... then Explode. nSwap in Darkmoon ZepplinnIf Frill Blast is available use DecoynElse use Missile until Darkmoon Zepplion dies and ressurects...n... then Explode.

This has only been tested once, but it seems to work....
Darkmoon Zepplin 1-2-2, Dranei Micro Defender 2-2-1, lvl1+ carry pet.

Start with Darkmoon Zepplin. Decoy to avoid forced swap and prevents some damage then Missile until Zepplin dies and resurrects then Explode.
Swap in Dranei Micro Defender. Batter until Frill Blast comes off cooldown then Shield Block to prevent the forced swap and block some damage. Resume Battering until Oondasta health is below 560 then explode. Oondasta should die and carry pet gets the XP.

I brought a level 15 mechanical carry pet (rocket chicken). Swapped him after scorpid died, the swapped to micro defender and followed the rest of the strat. Worked perfect, he servived and boosted 3 levels. Not too shabby.